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tracing: Add unstable sched clock note to the warning

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The warning "Delta way too big" warning might appear on a system with
unstable shed clock right after the system is resumed and tracing
was enabled during the suspend.

Since it's not realy bug, and the unstable sched clock is working
fast and reliable otherwise, Steven suggested to keep using the
sched clock in any case and just to make note in the warning itself.

Signed-off-by: Jiri Olsa <jolsa@redhat.com>
LKML-Reference: <1296649698-6003-1-git-send-email-jolsa@redhat.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
This commit is contained in:
Jiri Olsa 2011-02-02 13:28:18 +01:00 committed by Steven Rostedt
parent ae07f551c4
commit 5e38ca8f3e
1 changed files with 6 additions and 2 deletions
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8
kernel/trace/ring_buffer.c
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@ -2163,10 +2163,14 @@ rb_reserve_next_event(struct ring_buffer *buffer,
delta = diff;
if (unlikely(test_time_stamp(delta))) {
WARN_ONCE(delta > (1ULL << 59),
KERN_WARNING "Delta way too big! %llu ts=%llu write stamp = %llu\n",
KERN_WARNING "Delta way too big! %llu ts=%llu write stamp = %llu\n%s",
(unsigned long long)delta,
(unsigned long long)ts,
(unsigned long long)cpu_buffer->write_stamp);
(unsigned long long)cpu_buffer->write_stamp,
sched_clock_stable ? "" :
"If you just came from a suspend/resume,\n"
"please switch to the trace global clock:\n"
" echo global > /sys/kernel/debug/tracing/trace_clock\n");
add_timestamp = 1;
}
}